What causes headaches? – By Dan Kwartler

https://ed.ted.com/lessons/what-causes-headaches-dan-kwartler

I rarely get headaches, but I know people who often get them. They can be debilitating. Half of headaches seem to come from the head itself- these primary headaches are difficult to fathom. However, the secondary headaches that come from other conditions are easier to spot and treat.